1 files changed, 51 insertions, 0 deletions
diff --git a/compiler/rustc_driver_impl/src/args.rs b/compiler/rustc_driver_impl/src/args.rs
new file mode 100644
index 000000000..42c97cc6a
--- /dev/null
+++ b/compiler/rustc_driver_impl/src/args.rs
@@ -0,0 +1,51 @@
+use std::error;
+use std::fmt;
+use std::fs;
+use std::io;
+
+fn arg_expand(arg: String) -> Result<Vec<String>, Error> {
+    if let Some(path) = arg.strip_prefix('@') {
+        let file = match fs::read_to_string(path) {
+            Ok(file) => file,
+            Err(ref err) if err.kind() == io::ErrorKind::InvalidData => {
+                return Err(Error::Utf8Error(Some(path.to_string())));
+            }
+            Err(err) => return Err(Error::IOError(path.to_string(), err)),
+        };
+        Ok(file.lines().map(ToString::to_string).collect())
+    } else {
+        Ok(vec![arg])
+    }
+}
+
+pub fn arg_expand_all(at_args: &[String]) -> Vec<String> {
+    let mut args = Vec::new();
+    for arg in at_args {
+        match arg_expand(arg.clone()) {
+            Ok(arg) => args.extend(arg),
+            Err(err) => rustc_session::early_error(
+                rustc_session::config::ErrorOutputType::default(),
+                &format!("Failed to load argument file: {err}"),
+            ),
+        }
+    }
+    args
+}
+
+#[derive(Debug)]
+pub enum Error {
+    Utf8Error(Option<String>),
+    IOError(String, io::Error),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::Utf8Error(None) => write!(fmt, "Utf8 error"),
+            Error::Utf8Error(Some(path)) => write!(fmt, "Utf8 error in {path}"),
+            Error::IOError(path, err) => write!(fmt, "IO Error: {path}: {err}"),
+        }
+    }
+}
+
+impl error::Error for Error {}